Catalytic Allylic Oxidation of Internal Alkenes to a MultifunctionalChiral Building Block

摘要

The stereoselective oxidation of hydrocarbons represents one of the most significant advances in synthetic chemistry over the last fifty years^–. Inspired by nature, chemists have developed enantioselective dihydroxylations, epoxidations, and other oxidations of unsaturated hydrocarbons. More recently, the catalytic enantioselective allylic C–H oxidation of alkenes has emerged as a powerful chemical strategy, streamlining the production of pharmaceuticals, natural products, fine chemicals and other functional materials^–. Allylic functionalization provides a direct path to chiral synthons with a newly formed stereocenter from petrochemical feedstocks while preserving the olefin functionality as a handle for further elaboration. Various metal-based catalysts have been discovered for the enantioselective allylic C–H oxidation of simple alkenes with cyclic or terminal double bonds^–. However, a general and selective allylic oxidation remains elusive with the more common internal alkenes. Here, we report the enantioselective, regioselective, and E/Z selective allylic oxidation of unactivated internal alkenes via a catalytic asymmetric hetero-ene reaction with a chalcogen-based oxidant. This method represents the first example of selectively converting unsymmetrical internal alkenes into allylicfunctionalized products with high stereoselectivity and regioselectivity.Stereospecific transformations of the multifunctional allylic oxidation productshighlight the potential for rapidly converting internal alkenes into a broadrange of enantioenriched structures that can be utilized in the synthesis ofcomplex target molecules.